Vacuum casting machines



Feb. 23, 1965 e. HARRISON ETAL 3,170,203

- VACUUM CASTING MACHINES Filed Oct. 28, 1960 6 Sheets-Sheet 1 INVENTORS GEORGE HARRISON E; LSON K-HARRISON 570M111 viz ATTORN YS.

Feb. 23, 1965 e. HARRISON ETAL 3,170,203

VACUUM CASTING mcamas Filed ou. 28, 1960 e Sheets-Sheet 2 Feb. 23, 1965 G. HARRISON ETAL VACUUM CASTING MACHINES 6 Sheets-Sheet 3 Filed Oct. 28, 1960 Feb. 23, 1965 G. HARRISON ETAL VACUUM CASTING MACHINES 6 Sheets-Sheet 4 Filed Oct. 28, 1960 3 04142347 r Q ZQZ 98 ATTORN vs Feb. 23, 1965 G. HARRISON E'TAL 3,170,203

' VACUUM CASTING MACHINES Filed Oct. 28, 1960 6 Sheets-Sheets ill . age.

3,170,203 VACUUM CATING MACH-2mm George Harrison, 69% W. 39th St, Berwyn, Ill and Nelson Harrison, 432 Shenstoue Road, Riverside, lll. Filed Get. 23, won, Ser. No. 65,732 9 Claims. Cl. 22-73) The present invention relates to casting, and particularly to a new and improved automatic casting machine. In the metal arts, many finished products are made from die cast slugs of metal which are of a precise size,

and shape.

An object of this invention is to provide an automatic casting machine that will produce castings of a precise size and shape having a uniform density throughout.

Another object of this invention is to provide an automatic casting machine that controls the flow or" molten metal into the die in a mariner to avoid turbulence of the molten metal. I

, Another object of the invention is to provide such a casting machine in which the die is mounted on a swin ing arm to transport the cast slugs to a location where they may be deposited for a further treatment or stor- Another object of this invention is to provide anautomatic casting machinein which separable mating die and pan elements are immersed within a bath of molten metal in a manner to cause the, molten metal to flow upwardly through sprue openings in the bottom of thepan, or wherein the metal is caused to flow through the sprue openings, thenceinto the die cavities, and in which the sprues are automatically shearedofl aftersolidification of control may beprovided, for causing the mating die and the metal by a-relatively rotary motion between the die andpan. Another object of this inventionis to provide such an automatic casting machine) in' which a positive sprue. knock-outdevice is employed to clear the entrance passages within the bottom of the die pan. i

' Still another object of this invention is to provide such an automatic castingmachine in which the sprue knock out device isintegrally attached to the die pan and ar- 3,116,203 Patented Feb. 23, 39%5 "ice i The yoke member may be connected to vertically. reciprocable piston means so that the pan and die arm can be made to move vertically together as well as vertically relatively to each other.

In still another aspect of the invention, an adjustable abutment member may be attached to the standard on the carriage for'cooperation With an abutment means movable with the pan arm yoke member to limit the vertical movement of the pan relatively to the vertical movement ofthe die arm. a

In another aspect of the invention, a sprue knock-out device may be pivotally attached to the die pan in such a way that inits one pivoted position it does not interfere with the die, and in its other pivotal position it causes knock-out elementsto become aligned with the sprue openings in the bottom of the pan. Power operated means may be provided for pivoting the knock-outdevice between its two limiting positions and for causing the sprue knock-out elements to extract the sprue portions remaining in saidopenings.

In still another aspect of the invention, a variable vol- V ume cylinder device may be connectedinto a hydraulic line supplying the liquid for raising the die arm so that the degree of vertical movement of saiddie arm may be controlled. The variable volume can be provided for in other ways. a

In still'anotheraspect of the invention, a sequential die panto be lowered into a bath of molten metal until the die cavities are filled and the metal therein solidified; raising the mating die pan die to predetermined elevation and providing relative rotation between the two to shear-"off the sprues; causing the die arm to move up-' wardly independently of the pan to clear thelatter; turn ing the die arm away't'rorn the pan; pivoting the sprue knockout device into the pan and removing the sprue ranged so that no interference occunsbetween it and the'relatively'movable die arm i f Stillanother object of the invention support a standarcl tolwhich a vertically extendingcylinder may betixed and within which a reciprocable: piston and piston rodmay belocated. An overhanging arm may be journaled to'thetop of the piston rod', :and its free end may support a relatively rotatable die ha'yingcavities therein of any desired shape depending upon the form 'of castin gs'desired.

high torqueat the beginning ahd end of the travel of the In still another aspect of the invention, 'a crank arm may be mountedxon the. swingable, die arm for oscillating the die to shear off the spruesfbetween the die and .the

die pan.

In another aspect ofthe invention, the standard on" 1 the carriage may support spaced guide bearings within which may reciprocate parallel spaced legs that are connected to a yoke member to which an overhanging" arm is attached for supporting the die pan in alignmentwith the is to'provide such ;;-a casting machine in which the extent of movement of the:relativelymovable die and die pan may bevaried to a suit different requirements. k a I In oneaspect of the inventiorn' a portable carriage may portions within the sprue openings in the pan bottom; pivoting the sprue knock-out device out of the pan; re-

turning the die arm so that ;thedie is aligned with the pan; and lowering the die arm so, that the die mates a with the pan and forcest-he pan downwardly into thebath of molten metal for another charge;

The invention. also canbe usedwith other types of metalforming wherein the forming means is lowered into a bath of metal such as where a machining operation is performed on metal while in the bath as it is being formed orf 'solidifiedon aform. Also, itycan be employed with other-fmeans for causingthe molten metal to flow into automatic casting machinewnl become apparent from the'dies. N

The above; other. objects and novel features of the the following specification and accompanying drawings 2 ;which are merely exemplary! Inthe drawings:

die When-the latter is in one of its swingable positions.

fly along plane 2 2-of FIG. 1;'

line 3 3 of FIG. 2;

"unsa e of FIGS. 2 and 7; e

' F1617 is an elevational view taken along linef7-7 of I 551G. 1 is a perspective view of an automatic casting machine to Whichlhe principles. of the invention have been appliedyr FIG. 2 is asectional elevational view taken substantia FIG. 3 is an enlarged fragmentary view taken along .EIG. 4 is an. enlarged front elevational view of part of the machine shown in FIGpl, with certain parts in a different position from that shown in FIG. 1, the rotatable armbeing in an upper'position and turned; FIG. 5 is a detail of aportion'of the apparatus shown in FlG. 4 with certain parts in a diiferentposition from that shownin FIGA;

FIG. 6 is a sectional plan View taken FIG, 2; and

substantially along FIG. 8 is a circuit diagram for causing the sequential operation of the various elements of the invention.

Referring to the drawings, and particularly to FIG. 1,

the principles of the invention are shown as applied to a casting or similar machine including a carriage 10 having adjustable brackets 11 at each corner thereof on which rollers 12 and 13 are journaled. Track members 14 and 15 may be connected together by cross bars 16. The track member 14 may be an angle member and the rollers 12 may be grooved to receive the edge 17 of the angle member. The track member 15 may be flat bar stock and the rollers 13 may be cylindrical. The carriage 10 may have fixed to it a vertical standard including a front wall 18 and spaced side walls 19 (FIGS. 2 and 6). A vertically disposed cylinder 20 (FIG. 2) may be mounted on the carriage 10 between the side walls 19 thereof, and a piston 21 within cylinder 20 may have a piston rod 22 extending vertically above the cylinder 20. A stud 23 may be fixed to the rod 22, and a hub 24 may be rotatably mounted on stud 23 in bearings 25 and 26.

A horizontally disposed bracket 27 extends rearwardly of the machine from the top of the standard 18, 19 and may include a hollow, semicircular portion 28 (FIG. 1) for a purpose to be described later, bracket 27 and portion 28 being of one piece. A non-rotatable block 29 (FIG. 2) surrounds, and is fixed to, the stud 23 and on which the inner race of bearing 26 rests. The block 29 may have fixed to it a downwardly extending slide bearing 28A that rides within bearing ways 27 and 26 (FIG. 6) bolted to the front wall 18 of the standard on the carrier 10. This construction provides rigidity to the vertically reciprocable, rotatable hub 24 (FIG. 2). A recess 30 formed by the hollow,- semicircular portion 28 is adapted to receive a hydraulic motor 31 that is supported by a bracket 32 fixed to the block 29. The output shaft of the motor 31 may have a crank arm 33 fixed thereto, and a roller 34 on arm 33 may engage a groove 7 from it, and it may comprise walls 39 and 40 (FIG. 3)

between which are provided ribs 41 that support a hub 42. The hub 42 has a bolt 43 journaled therein which supports a die 44 that includes a plate 45 that has'bolted to it a roller guide 46 having a roller groove 47 therein. A bracket 48, fixed to hub 24, may support a hydraulic motor 49 to the output shaft of which a crank arm 50 is connected. A roller 51 on crank arm 50 rides within groove 47. The construction and arrangement of the parts are such that oscillation of motor 49 causes arm 45 to move from its solid line position 52 to its dot and dash line position 53 and back again (FIG. 3). This causes die 44 to oscillate about the axis of bolt 43 for a purpose to be described later.

Referring to FIG. 2, a die pan 54 may be fixed to the outer end of an arm 55 by a bolt 56. The arm 55 may be I integrally attached to a yoke 56' (FIG. 7) including spaced vertical rails 57 and 58 that ride in giude bearings 59 and 60 (FIG. 6) formed in the front wall 18 of the standard on carriage 10;

Referring to FIG. 7, the yoke 56 may include ears 61 and 62 from which vertically extending piston rods 63 and 64 depend. The rods 63 and 64 support pistons within air cylinders 65 and 66.

Vertically extending plates 67 and 68 (FIG.- 6), fixed to wall 18, rigidly support upper and lower cross bars 69 and 70. These cross bars rigidly support a threaded abutment rod 71 in a manner such that its lowerend '72 can be adjusted to different elevations. A frame member 73 is bolted to the yoke 56 by bolts 74 and it may sur- I round the rod 71 in a manner such that a bottom wall 75 thereof is in alignment with the end 72 of rod 71.

From the foregoing its is evident that air under pressure admitted beneath the pistons in cylinders 65 and 66 from an air storage tank 66 will cause the yoke 56, and with it pan 54, to move upwardly until bottom wall 75 of frame 73 abuts the end 72 of rod 71, all for a purpose to be described later.

Referring again to FIG. 2, the connection between pan 54 and arm 55 may include a guide recess 76 into which a guide pin 77 mounted in the web framing 41 is adapted to extend in order to cause, with the mating of pin 28' and recess 28" also, perfect mating between the die 44 and the pan 54. An elongated recess 76' may be provided in plate 45 through which guide pin 77 extends for permitting oscillatory motion of plate 45 about the axis of bolt 43. The die 44 may include cavities 78 that must be accurately aligned with sprue openings 79 in the bottom wall of pan 54. Flexible air lines (not shown) may be connected to ducts 80 extending upwardly through the die 44 and the plate 45.

As shown in FIG. 2, the mating die 44 and pan 54 are immersed in a bath 81 within a crucible 82. The construction of the die 44 is such that the application of suction to the lines 80 removes entrapped air. Such is more fully described in US. Patent 2,863,188 to which attention is directed for further details of the die construction.

Referring to FIGS. 1, 4 and 5, the pan 54 may include a support base 83 fixed to its rim 54. The bracket 83 may include a shaft 84 journaled in upstanding ears 85. A floating guide 86 is journaled on shaft 84 and is of such length as to extend across the pan 54, and in its one oscillatable position to engage a saddle guide 87 on the pan rim 54', diametrically opposite the support base 8-3. The floating guide 86 may include spaced parallel walls 88 and 89, between which a gear segment 90 may be located. The segment 90 may be keyed to the shaft 84 and may mesh with a rack 91 that is mounted for reciprocation within a guide 9.2 rigidly mounted between the walls 88 and 89 of the floating guide 86.

A knock-out plate 93 may include knock-out pins 94 extending from its one face and arranged to mate with the entrance holes 79 in the bottom of the pan 54. The

- plate 93 may be resiliently supported from brackets 95, 45

fixed to the floating guide 86, through springs 96 and 97 which latter normally maintain plate 93 in engagement with the bottom end of rack 91.

The construction and arrangement of the parts of the sprue knock-out device are such that as shaft 84 is rotated in a clockwise direction from the position shown in FIG. 1, all of the elements including the floating guide 86, the segment 90, the rack 91 and the plate 93 rotate in unison until the outer end of floating guide 86engages guide saddle S7. Continued clockwise motion of shaft 84 causes segment 90 to continue to turn in a clockwise direction, thereby forcing rack 91 and plate 93 downwardly against the action of springs 96 and 97 to the position shown in FIG. 5 where the knock-out pins 94 mate with the entrance openings 79 in the bottom of pan 54 and eject the sprue portions 98 therefrom.

Counterclockwise movement of shaft 84 will cause theparts of the knock-out device to assume the positions shown in FIGS. 4 and 1, respectively, thereby moving the knock-out device clear of the pan 54 so that the die 44 can mate therewith without interference from the knockout device. a

Referring to FIG. 1, shaft 84 may be connected through universal joints 99 and 100 and a drive shaft 101 to a hydraulic motor 102 adapted to oscillate shaft 84 in a manner to produce the described action of the knock-out device.

In order to control the low point of travel of the swinging arm and consequently the low point of travel of the pan 54, a variable stroke piston and cylinder device 103 may be provided. It may include a floating piston, the

' stroke of which can be varied by an adjusting screw 104.

As supply oil is forced under pressure on-the top of the floatingpiston, the oil beneath the piston will be forced into cylinder 20, causing the raising of the swinging'arm 38. V

With the apparatus in the position shown in FIG. 2, suction may beapplied to the ducts 8th, and the mating die :4 and pan 54 are retained within bath 81 of molten metal for a predetermined period by an appropriate timing device, ensuring the complete filling of thecavities 78 with molten metal which begins to solidify from within the die 44 outwardly toward the entrance holes '79 in the bottom of the pan 54. After this predetermined time period, the

timing devicemay energize a solenoid 105 (FIG. 8) to cause pressure liquid to flow from a reservoir 1% to the inlet of a pump 107 that is driven by a motor 108. The

output of pump 107 may flow through a valve block 109,

a line 110, and into the variable stroke cylinder device 103, forcing the liquid beneath its piston into cylinder 2% beneath the piston therein to cause the swinging arm 38- to begin rising. Air under pressure within storage cylinder 66' acts on the cylinder devices 65 and 66 (FIG. 1) to cause the yoke 55, pan arm 55, and pan 54 to move upwardly with the die 44 and swinging arm 38.

Just prior to the bottom 75 of the frame 73 (FIG. 7) engaging the bottom '72 of the rod 71, for limiting the upward travel of the pan 54 to a position above the bath 81, a solenoid 111 (FIG. 8) may be energized, causing the supply liquid from line 116 to pass through a line 112, motor 49, and an exhaust line 112' leading to the reservoir .of molten metal.

reservoir 1%. As the arm 33 descends, the die. 44 picks up the pan 54, forcing it downwardly toward the bath 81 As the mating die .44- and pan 54 approach the bath 81, thelocatirig pins 77 and 28' cooperate with their corresponding guide holes '76 and 28" to accurately align the die 44 with the entrance openings of the pan 5 5. As the pin 28' passes upwardlythrough the guide hole 28", it may close a switch 139 for energizing a solenoid 1126 that reduces the rate of flow of liquid exhausting from cylinder 1%, thereby to slow down the movement ofthe pan 5d and die 44 into the bath'fil, after which the above described cycle is repeated.

As mentioned, other types of metal forming devices which are lowered into the molten metal can be fastened to the lower arm and/ or the swinging die arm, or pressure or other type feeding means can be employed to feed metal to the die.

It is to be noted that at normal initial turning positions of arms 38 and 32, maximum torque will bejdeveloped 1%, thereby rotating the hydraulic motor 49 in one direction and causing plate 45 (FIG. 2) to move about the axis of bolt 43 from the position 52 to the position 53 (FIG. 3). This action provides a rotary motion to the die 44 relatively to the pan 54, thereby shearing off the sprues extending through holes 79 in the bottom of pan 54, leaving the sheared olf portions within said holes.

When the plate '45 reaches its position 53 (FIG. 3), a solenoid 113 may be energized, causing a reversal of the flow of pressure liquid tothe motor 49, thereby returning plate 45 to the position 52. where it remains until the next cycle of operations.

Since the rod 71 has stopped the upward movement of the pan 54, continued upward movement of the swinging arm 33 causes died-d to separate from pan 54. When the die 44 clears the'pan 54, a solenoid may be energized, causing hydraulic motor 31 to rotate, thereby turning swinging arm 38 about the bearings 25 and 2.6 since the supplying pressure fluid beneath the piston in saidfcylinthe cavities 78 are to bedeposited, air under pressure may be supplied to the ducts 8t forcing the castings out of their respective cavities. I

With the swinging arm 38 at the location for depositing the cast slugs, a solenoid 115 may be energized, causing supply pressure liquid to rotate the hydraulic motor 162 to elfect turning of the shaft 84 and floating guide 86 in a clockwise direction until the latter engages saddle $7, whereupon continued clockwise rotation of shaft 84 forces rack 5 and with it knock-out plate 93 to eject the sprue portions ,93 within the entrance openings 7? of the pan 54. When the knock-out plate has performed its function, a solenoid 1% may be energized, reversing the flow of liquid to the motor ltlZ and causing the knock-out device to be returned to the position shown in FlGQ l where it remains until another cycle of operations. When the knock-out device has returned to the position shown in FIG. 1, and the slugs have been deposited from the die ergized, causing the pressure liquid above the floating pis ton in cylinder 1633 to exhaust through line 112" to the by their respective turning meansbecause of the relation of the arms'Sil and 33, respectively, thereto.

Although the various features of the new and improved automatic casting machine have been shown and described in detail to fully disclose one embodiment of the invention, it will be evident that numerous. change or reversal of parts may be made in such details and certain features may be used without others without departing rom the principles of the invention.

What is claimed is:

' 1. In a casting machine, a support; a vertical standard on said support; a vertical cylinder on said support adja cent said standard; a piston within said cylinder having a piston rod extending outwardly, above said cylinder; a block fixed to said piston rod; a rotatable arm supported by said block and journaled on said piston rod; a cast-v ing diehaving cavities therein fixed tosaid arm; a hori- 1 zont al frame fixed to said standard, surrounding said piston rod and providing a recess between said piston rod and theouter-extreniity of said frame; a motor-fixedto said block and supported Within saidrecess and including means for angularly turning said arm; and means for der for raising said rotatable arm.

2. In a casting machine, a support; a vertical standard on said support; a vertical cylinder on said support adjacent said standard; a piston within said cylinder having a piston rod extending outwardly, above said cylinder; a

block fixed to said piston rod; a rotatable arm supported.

by said block and journaled on said pistonrod; a casting die having cavities therein fixed to said arm; a horizontal frame fixed to said standard, surrounding said piston rod and providing a recess between said piston rod and the outer extremity of said. frame; a motor fixed to said block and supported within said recess and including means for angularly turning said arm; means on said arm for oscillating said casting die; and means for supplying pressure fluid beneath the piston in said cylinder for raising said rotatable arm.

3. In a casting machine, a support; a vertical standard on said support; a vertical cylinder on said support adjacent said standard; a piston within said cylinder having a piston rod extending outwardly, above said cylinder; a. block fixed to said piston rod; a rotatable arm supported by said block and journaled onsaid piston rod; a casting die having cavities therein fixed to said-arm; a horizontal frame fixed to said standard, surrounding said piston rod frame and said rotatable arm for locating said arm in one of its rotatable positions, I V V 4. In a casting machine, a vertically reciprocable, rotatable arm; a rotatable casting die connected to said arm; a Vertically reciprocable, non-rotatable arm; a nonrotatable pan connected to said non-rotatable arm in alignment with said die in one of the rotatable positions of said rotatable arm; means for maintaining said pan in contact with said die during a portion of the vertical movement of said rotatable arm; means for rotating said rotatable die while said die and pan are in contact; and means for rotating said rotatable arm when it is at a position above the uppermost position of said non-rotatable arm to move said die out of alignment with said pan.

5. In a casting machine, a vertically reciprocable, rotatable arm; a casting die connected to said arm; a vertically reciprocable, non-rotatable arm; a pan connected to said non-rotatable arm in alignment with said die in one of the rotatable positions of said rotatable arm; means for maintaining said pan in contact with said die during a portion of the vertical movement of said rotatable arm; means for providing relative rotary motion between said die and pan while they are in contact; means for rotating said rotatable arm when it is at a position above the uppermost position of said non-rotatable arm to move said die out of alignment with said pan; hydraulic means for vertically reciprocating said rotatable arm; and pneumatic means for vertically reciprocating said non-rotatable arm.

6. A sprue knock-out device for a casting machine of the type that includes a pan having a perforated bottom that cooperates with a separable die having cavities that communicate with said perforations, and in which relative rotary motion is provided between the die and pan to sever the sprues, comprising a bracket fixed to the side of said pan; a shaft oscillatably mounted in said bracket; a guide member pivoted to said shaft and adapted to extend across said pan in its one pivotal position; a slide bearing fixed to said guide member; a rack within said bearing; a gear segment fixed to said shaft and meshing with said rack; a plate resiliently mounted in abutting relation to one end of said rack and including ejecting pins adapted to register with the perforations in said pan; and means for oscillating said shaft.

7. A sprue knock-out device for a casting machine of the type that includes a pan having a perforated bottom that cooperates with a separable die having cavities that communicate with said perforations, and in which relative rotary motion is provided between the die and pan to sever the sprues, comprising a bracket fixed to the side of said pan; a shaft oscillatably mounted in said bracket; a guide member pivoted to said shaft and adapted to extend across said pan in its one pivotal position; a resiliently mounted sprue knock-out plate supported by said guide member including sprue knock-out pins adapted to register with the perforations in said pan; and means for moving said guide member and said knock-out plate in unison into and out of cooperating position with said perforations.

8. In a casting machine, a vertically reciprocable, ro-

tatable arm; means for rotating said rotatable arm; a rotatable casting die connected to said arm and provided with cavities; means for rotating said die; a vertically reciprocable, non-rotatable arm; a pan having a perforated bottom connected to said non-rotatable arm in alignment with said die in one of the rotatable positions of said rotatable arm; pneumatic means for maintaining said pan in contact with said die with the perforations in communication with the cavities of said die during only a portion of the vertical movement of said rotatable arm; a sprue knock-out device pivotally mounted on one side of said pan and normally maintained in an ineffective, non-interfering position with said die; means for pivoting said knock-out means from said ineffective position to an effective position; cyclic operating means for controlling said machine including means for raising said rotatable arm; means responsive to the vertical movement of the non-rotatable arm for energizing said die rotating means to shear the sprues within the perforations of said pan from the castings within the die cavities; means responsive to the rotatable arm reaching its uppermost position for energizing said arm rotating means; and means responsive to the rotation of said rotatable arm for energizing said knock-out rotatable means.

9. In a casting machine, a vertically reciprocable, rotatable arm; hydraulic means for rotating said rotatable arm; a rotatable casting die connected to said arm and provided with cavities; hydraulic means for rotating said die; a vertically reciprocable, non-rotatable arm; a pan having a perforated bottom connected to said n0n-rotata ble arm in alignment with said die in one of the rotatable I positions of said rotatable arm; pneumatic means for maintaining said pan in contact with said die with the perforations in communication with the cavities of said die during only a portion of the vertical movement of said rotatable arm; a sprue knock-out device pivotally mounted on one side of said pan and normally maintained in an ineffective, non-interfering position with said die; hydraulic means for pivoting said knock-out means from said ineffective position to an effective position; cyclic operating means for controlling said machine including means for raising said rotatable arm; means responsive to the vertical movement of the non-rotatable arm for energizing said die'rotating means to shear the sprues within the perforations of said pan from the castings within the die cavities; means responsive to the rotatable arm reaching its uppermost position for energizing said hydraulic arm rotating means; and means responsive to the rotation of said rotatable arm for energizing said knock-out rotatable means.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A CASTING MACHINE, A SUPPORT; A VERTICAL STANDARD ON SAID SUPPORT; A VERTICAL CYLINDER ON SAID SUPPORT ADJACENT SAID STANDARD; A PISTON WITHIN SAID CYLINDER HAVING A PISTON ROD EXTENDING OUTWARDLY, ABOVE SAID CYLINDER; A BLOCK FIXED TO SAID PISTON ROD; A ROTATABLE ARM SUPPORTED BY SAID BLOCK AND JOURNALED ON SAID PISTON ROD; A CASTING DIE HAVING CAVITIES THEREIN FIXED TO SAID ARM; A HORIZONTAL FRAME FIXED TO SAID STANDARD, SURROUNDING SAID PISTON ROD AND PROVIDING A RECESS BETWEEN SAID PISTON ROD AND THE OUTER EXTREMITY OF SAID FRAME; A MOTOR FIXED TO SAID BLOCK AND SUPPORTED WITHIN SAID RECESS AND INCLUDING MEANS FOR ANGULARLY TURNING SAID ARM, AND MEANS FOR SUPPLYING PRESSURE FLUID BENEATH THE PISTON IN SAID CYLINDER FOR RAISING SAID ROTATABLE ARM. 